10 years ago today a Putin critic died of radiation poisoning — here are others who have ended up dead

Ten years ago today, Alexander Litvinenko died from radiation poisoning in a hospital bed in London.

Litvinenko, a defector from the Russia's intelligence service the FSB, was a prominent critic of Putin and the Kremlin.

He died from ingesting a dose of the radioactive material polonium-210, which a British inquiry in 2016 found was most likely a political assassination approved by the head of the FSB and Russian President Vladimir Putin.

Litvinenko's death is one among a series of mysterious killings. Here are some of the other people Putin is suspected of assassinating:

Mikhail Lesin

The Washington DC medical examiner's office has confirmed that former Russian press minister Mikhail Lesin died of "blunt force trauma to the head."

Lesin, who founded the English-language television network Russia Today (RT) was found dead in a Washington, DC, hotel room in November 2015.

The Daily Beast reports that before his death, Lesin was considering making a deal with the FBI to protect himself from corruption charges.

For years, Lesin had been at the heart of political life in Russia and would have known a lot about the inner workings of the rich and powerful.

Anna Politkovskaya

Anna Politkovskaya was a Russian journalist who was critical of Putin. In her book "Putin's Russia," she accused Putin of turning his country into a police state. She was murdered by contract killers who shot her at point blank range in the lift outside her flat.

Five men were convicted of her murder, but the judge found that it was a contract killing, with $150,000 paid by "a person unknown."

A picture of slain journalist Anna Politkovskaya is shown during a candlelight vigil in front of the Russian Embassy. Mark Wilson/Getty Images

Natalia Estemirova

Natalia Estemirova was a journalist who sometimes worked with Politkovskaya.

Boris Nemtsov

Boris Nemtsov was a former deputy prime minister of Russia under Boris Yeltsin who went on to become a big critic of Putin — accusing him of being in the pay of oligarchs.

He was shot four times in the back just yards from the Kremlin as he walked home from a restaurant. Despite Putin taking "personal control" of the investigation into Nemtsov's murder, the killer has not been found.

Boris Berezovsky

Boris Berezovsky was a Russian oligarch who fled to Britain after he fell out with Putin. During his exile he threatened to bring down Putin by force. He was found dead at his Berkshire home in March 2013 in an apparent suicide, although an inquest into his death recorded an open verdict.